In Situ Growth of Strained Matrix on CsPbI 3 Perovskite Quantum Dots for Balanced Conductivity and Stability.

Their nanoscale size endows perovskite quantum dots (QDs) with processing flexibility and high tunability of optoelectronic properties. The vast surface area also provides an opportunity for ligand engineering to offer QDs extra protection, which however, will impede charge transport in the QD array. Currently, the surface treatments that can balance both stability and conductivity of the perovskite QD array remain a huge challenge. Here, we report in situ growth of an atomic guanidinium lead iodide perovskite matrix on CsPbI 3 QDs. In addition to the effect of trap passivation, the matrix can also provide substantial surface strain to improve the QD phase stability. Meanwhile, the ultrathin matrix allows efficient coupling and charge transport in the QD solids. As a result, the CsPbI 3 QD solar cells can achieve both superior device stability and performance. We believe the development of a multifunctional surface matrix will become one of the future research focuses in perovskite QD-based devices.